Method of vulcanizing rubber



not soluble in or tlcco'mposetl by water.

Fatenteal a l-pal "W253i."

czar rou nsnnonn, or AKRON, 0am, ASSIGNOR To THE GOODYEAR TIRE & RUB

BER CQMPANY, GE AKB.0N., OHIO. A CORBORATION OHIO.

IVIETHC'D OF VtlLCANIZING RUBBER.

1m nmwm I .Application and August 16, 1921. Serial No. 492,825. .TOIZU l'cl'iom i2 i'lllll/i (UIl/Y'INJ in investigatingthe work of Schill. l

Be it known that 1. (lnrr'rox W. Bnoroun, observed, in working with dilute solutions a citizen'ol the-l 'niteilSlates. residing at of ziucsalts and sodium pentasullhle. the Akronyin the county of Summit an l State. following phenomena: large amount ot a 6 of Ohio, have inyentegl new and useful zinc solution. preferably the acetate. may be W) Improvements in Methods of \'ulcanizin 2l(l l((l to a dilute sodium poutasulliile solo-- Rubheigot which the 'lollowing is a speci; lion without causing a precipitate to l'ormv ficationQ This is illustrated by the following equiv- My invention relates to the ruleaniyiatiou tions as similar to the :uhliti'on ol a solution In or curing of camitchouc substances aml. it oi zinc salts to a solution of caustic Sulln 1! has, for its primary object the provision of without precipitation. "'ulchhlzlhg gent which Shall he l-I h' i. Zn(Ac)z+4N:\0H 2NuAc+Zn(0Nahsoluble-l 211m. elficient in operation and which shall insure 2. Zn(Ac)z+2Nu S)2NnAc +ZntSNzUgsoluble.

' obtaining a high qualityproduct. .7 v a- KAOH2Nfl2SIr l 'llc'retofore, the use of n'ietallic polysul- F b t gi ti f th {i i; twp 7 fides has been limited almost entir y to tions, reference may be made to an article antimony polysulfiiles, although arsenic by Thomson (Ber. 11 (i878) 2044) on Ziiu polysulfiiles have also,..beeii recognized as sulfhydrates. l useful in the curing'ot rubber or rubbeu llp on further-addition of zine s lt, ,1

compounds. On account of the lll L'll valency {l m a precipitate forms which is very .ot antimonyyit is necessary to utilize Iclw coll )ldtll in character and filters with great tively large amounts of its polysulliilc in LlllllClllhy or not at all.- The high molecular to pp y a efini fl 0f livellwveight of similar precipitates has been able sulfur for the vi'ilcanization of rubber, shown by Linder & Picton (J. C. S. (31

23 as compared to what would be necessary if. (1892) 114), Th t t i th ti 80 lts yalency W6l'G;lOWG1. I may, therefore, be. written as follows:

ihe polysulhtles 0t alkali and alkalinev 4h gzmsNnhJrZnMchHzNaAH(Nksrzksmzn earth metals are soluble in water and do not lencl themselves readily to the formation of dry compounding materials. Moreover, the

alkali polysulfides have the same deteriorating effect as free alkali upon the aging properties of rubber. The alkaline earth polysull'itlesare inconvei'iient tohamllc because they stain and all'ect the hands of the operator. The polysulliiles of zinc are yoli lowish white powders which have none of these disadvantages. They are. not alkaline in charactm', do not altect the skin and are Continuing, the addition of zinc salt solution', there finally results a granulation of the precipitate with excess ofthe zinc salt. The precipitate therefore consists of (Zn% with perhaps an acidiofor hydroxyl group on the owl zincv atoms or without the same by the closing of the. chain .ot no -ZnS links. I

' l also liml that similar reactions prom-ell with more or less su-ll'ur than S down to the use of Nafi without extra sulfur and that the precipitates so formed are capable of 95 I have now found that the insoluble polylhcklhg l f Sulfur h' pp Oh sulfides 'f metals, gspcciany those sulfur, tending to approach the most stable f i l bl i g agents d fi -d polysullicle compound which seems to be many h f t' -i ti advantages. Over the that of S whichv correspoluls to the qrouppolysulfides of triand penta-valent metals. hlg the Sulfate. radical loo Schilf (Lieh. Ann. 115 (1860) 74:) in an 7J0 article entitled The polysulfides of heavy metals has dealt with the ,polysulficles M m a large number of heavy metals other than. /S those of antimony and arsenic. He found s 105 most of them to be unstable and'only obp tainablev by special. precautions. He also and evidently consists of a b1valent group oil.

states that the polysulfioles of zine (lo not sulfur. atoms having a high degree of reeasily decompose and can easily be. isolated activity. aml manipulated. l have now lound that the porysulfitles of H0 zinc are valuable vulcanizing agents, as illus the product is found tobe over cured in 2 hours, under cured but Well set in 45 minutes, while in- 60 to 75 minutes, a good product is produced. Five per cent of ordinary sulfur will not give a satisfactory cure in less than about .hours.

It should be noted that free sulfur may be utilized with zinc persulfides, as Well as the usual compounding ingredients and the process, furthermore, is not limited to theuse of persulfide alone,

Other metals, withthe exception of antimony and arsenic, are limited in their use.

by the relative instability of their polysulfides or by being strongly alkaline and water a soluble.

Itwill be understood that the presentinventionishould not be limited by the specific examples which have been set forth, or by such theoretical statements as may have been made, nor is the invention dependent upon the soundness or accuracy of such theoretical statements and it should be restricted, therefore, only by the prior art and as indicated by the appended claims.

What I claim is: i

1. A process of vulcanizing rubber that comprises admixing a zinc persulfide with rubber and applying heat thereto.

2. A process of vulcanizing rubber that comprises admixing a Zinc pentasulfide with rubber and applying heat thereto.

A process of vulcanizing rubber that comprises admixing a zinc persulfide with rubber and inert fillers and applying heat thereto. I

4. A vulcanized rubber product produced by admixing zinc persulfide with rubber and applying heat thereto.

A vulcanized rubber product produced by admixing zinc pentasulfide with rubber and applying heat thereto.

6. A vulcanized rubber product produced by admixingzinc persulfide with rubber and inert fillers and heating the mixture.

In witness whereof I have hereunto si ned my name in the presence of two subscribing witnesses.

. CLAYTON W. BEDFORD. Witnesses:

L. M. HARTMAN, J. E. 'Kmrrne. 

